Transition Metal-Loaded TiO ₂ Catalyst for Catalytic Thermoliquefaction of Municipal Solid Waste into Carbon-Rich Oil

High Resolution Image Download MS PowerPoint Slide Continued fossil fuel depletion has accelerated the search for sustainable, clean energy solutions, positioning abundantly available biomass as a compelling pathway to meet global energy demand. The present study explores the use of an inexpensive transition metal-loaded TiO 2 catalyst for catalytic thermoliquefaction (mCTL) of the organic biodegradable municipal solid waste to produce carbon-dense mCTL oil at nonstringent reaction conditions. Various transition metal catalysts are synthesized as TiO 2 -loaded catalysts from their nitrate precursors and evaluated for mCTL. Of the synthesized catalysts (Cr/TiO 2, Ni/TiO 2, Fe/TiO 2, Co/TiO 2, and Cu/TiO 2 ), Co/TiO 2 shows excellent performance in terms of biomass conversion (>68%) and mCTL oil yield (>58%) without formation of char and gaseous byproducts at 200 °C. The optimized conditions using Co/TiO 2 provide biomass conversion (>84%) and mCTL oil yield (>77%) at 250 °C in 60 min. Various surface-morphological and analytical characterization techniques are explored to elucidate the catalyst's physicochemical and surface features. The synthesized Co/TiO 2 exhibits the presence of Co 2 O 3 and Co 3 O 4 with a crystalline phase and uniform Co loading on TiO 2 . Surface area analysis reveals a mesoporous structure with a specific surface area of 16.93 m 2 g −1 and pore diameters ranging from 8 to 16 nm. The obtained mCTL oil was characterized by acid number, elemental analysis, infrared spectroscopy, GC-MS, and HPLC, confirming the presence of a wide range of hydrocarbons, including acids, esters, alcohols, etc. Catalyst recyclability tests over five consecutive runs demonstrate consistent mCTL process performance. Additionally, environmental metrics, including the E-factor, process mass intensity (PMI), and water and carbon footprints, indicated the sustainability of the mCTL process, highlighting its strong potential to produce next-generation fuels, chemicals, and value-added products from municipal waste. Thus, cobalt was found to be a more efficient metal to promote the mCTL process, which may be because of its excellent balance of redox activity, hydrogenation ability, C−O bond cleavage efficiency, and thermal stability.